What is the difference between TaskTracker and JobTracker?

TaskTrackers will be assigned Mapper and Reducer tasks to execute by JobTracker. TaskTracker failure is not considered fatal. When a TaskTracker becomes unresponsive, JobTracker will assign the task executed by the TaskTracker to another node.

What is the difference between a NameNode and a DataNode?

The main difference between NameNode and DataNode in Hadoop is that the NameNode is the master node in HDFS that manages the file system metadata while the DataNode is a slave node in HDFS that stores the actual data as instructed by the NameNode. In brief, NameNode controls and manages a single or multiple data nodes.

What are the roles of JobTracker and TaskTracker in Hadoop?

JobTracker is a master which creates and runs the job. JobTracker which can run on the NameNode allocates the job to tasktrackers. It is tracking resource availability and task life cycle management, tracking its progress, fault tolerance etc. TaskTracker run the tasks and report the status of task to JobTracker.

What is the difference between a data node and a Nodemanager?

Datanodes are used to store data on HDFS whereas Nodemanagers are used to start a container on Yarn.

What are the roles of JobTracker and TaskTracker in MapReduce?

JobTracker receives the requests for MapReduce execution from the client. JobTracker talks to the NameNode to determine the location of the data. JobTracker finds the best TaskTracker nodes to execute tasks based on the data locality (proximity of the data) and the available slots to execute a task on a given node.

What is the use of JobTracker How does it vary from TaskTracker?

The TaskTracker performs its tasks while being closely monitored by JobTracker. If the job fails, JobTracker simply resubmits the job to another TaskTracker. However, JobTracker itself is a single point of failure, meaning if it fails the whole system goes down. JobTracker updates its status when the job completes.

What is a DataNode?

The DataNodes are responsible for serving read and write requests from the file system’s clients. The DataNodes also perform block creation, deletion, and replication upon instruction from the NameNode. The NameNode and DataNode are pieces of software designed to run on commodity machines.

What is the DataNode?

What is the function of JobTracker?

Job tracker’s function is resource management, tracking resource availability and tracking the progress of fault tolerance. Job tracker communicates with the Namenode to determine the location of data. Finds the task tracker nodes to execute the task on given nodes.

What is JobTracker and TaskTracker in MapReduce?

JobTracker – Manages MapReduce jobs, distributes individual tasks to machines running the Task Tracker. Following 2 Daemons run on each Slave nodes DataNode – Stores actual HDFS data blocks. TaskTracker – Responsible for instantiating and monitoring individual Map and Reduce tasks.

What is the difference between DataNode and NameNode and DataNode?

Each runs on its own, dedicated master node. NameNode stores MetaData (No of Blocks, On Which Rack which DataNode the data is stored and other details) about the data being stored in DataNodes whereas the DataNode stores the actual Data.

What is the difference between NameNode and TaskTracker?

Also namenode will never communicate with tasktracker and jobtracker will never communicate with datanode they work independently. However jobtracker will communicate with namenode to assign task to tasktracker. Next, mappers and reducers are the user programs executed on the data present in the datanode.

How are mapper and reducer tasks executed on DataNodes?

Mapper and Reducer tasks are executed on DataNodes administered by TaskTrackers. TaskTrackers will be assigned Mapper and Reducer tasks to execute by JobTracker. TaskTracker will be in constant communication with the JobTracker signalling the progress of the task in execution. TaskTracker failure is not considered fatal.

What is the difference between master node and slave node in HDFS?

Moreover, Master node is another name for NameNode while Slave node is another name for DataNode. While nameNode handles the metadata of all the files in HDFS and controls the dataNodes, Datanode store and retrieve blocks according to the master node’s instructions.